Evidence for a less differentiated subpopulation of lymphocytes in people of advanced age.

The ratio of the lactate dehydrogenase subunits, H/M, is shifted toward lower values in thymocytes, and in high-density T cells in normal peripheral blood. The results presented here indicate that the T cells, but not B cells or monocytes, of donors greater than 75 years' old have a significantly reduced H/M ratio relative to young adults. This reduced H/M ratio appears to be correlated with a diminished percentage of OKT3 positive cells in the old donors. However, the density distribution of cells from young and old on Percoll gradients indicates that the T cells with lower H/M ratio in the elderly may represent a distinct, and possibly unique, less differentiated T cell type.

Changes in lactic dehydrogenase isoenzyme pattern in muscle of tumor-bearing mice.

The lactic dehydrogenase isoenzyme distribution shifts gradually toward the isoenzyme pattern of the tumor in mouse muscles located distally from a transplanted mammary carcinoma.

Isoenzyme distribution of creatine kinase and lactate dehydrogenase in serum and skeletal muscle in Duchenne muscular dystrophy, collagen disease, and other muscular disorders.

We determined the total activity and isoenzyme distribution of lactate dehydrogenase and creatine kinase in serum and biopsy specimens from skeletal muscle of nine normal individuals and nine patients with Duchenne muscular dystrophy (I), five with collagen disease (II), and four with non-progressive unclassified myopathy (III). Mean total serum creatine kinase in patients with Duchenne muscular dystrophy (867 U/liter, SD = 197) was 31-fold that in the control group (28 U/liter, SD = 14). There was also a small (3.3-fold) increase in the mean total serum creatine kinase of patients with III, but none in the serum from patients with II. Changes in the creatine kinase isoenzyme distribution of skeletal muscle were primarily in the MB isoenzyme. The mean percentage of creatine kinase-MB activity in muscle from patients with I (2.81, SD = 1.15) and patients with III (1.69, SD = 1.07) significantly (P less than 0.005) exceeded that of the control group (0.43, SD = 0.18). Muscle from patients with II showed little change. The most striking changes in lactate dehydrogenase were also observed in patients with I, in whom the mean total serum activity (356 U/liter, SD = 115) was 3.4-fold that of serum from the control group (105 U/liter, SD = 19). Skeletal muscle from these patients also showed a significant decrease in mean percent isoenzyme 5 activity (from 50 to 23) and an increase in that of isoenzymes 1 and 2 (from 1 to 9 and 8 to 20, respectively). These changes in the distribution of these two sets of isoenzymes in muscle were reflected in the serum.

Adenosine deaminase activity in lymphocytes of normal persons, leukemic patients, and kidney-transplant recipients.

We determined the activity of adenosine deaminase in normal lymphocytes from peripheral blood, leukemic cells from patients with various hematologic malignancies, and mononuclear cells from kidney-transplant patients, by adapting the method of Hopkinson et al. [Ann. Hum. Genet. 32, 361 (1969)] to the centrifugal analyzer. Normal lymphocytes separated on Ficoll-Hypaque from peripheral blood had a mean activity of 1.42 U/10(9) cells (SD = 0.57; N = 33). Cells similarly isolated from patients with acute lymphoproliferative and myeloproliferative disease generally showed greater values, but the ranges overlapped. Cells from patients with chronic lymphocytic leukemia had activities that were within or below the normal range. Mononuclear cells isolated from the peripheral blood of 15 stable renal allograft recipients showed a mean activity of 1.90 U/10(9) cells (SD = 0.59), not significantly different from normal. In contrast, cells from five patients with biopsy-proven allograft rejection showed a mean activity of 12.84 U/10(9) cells (SD = 10.10), which was significantly different from that of the stable patients.